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Commit ed9b430c authored by Yan, Zheng's avatar Yan, Zheng Committed by Ilya Dryomov
Browse files

ceph: cleanup ceph_flush_snaps() 



This patch devide __ceph_flush_snaps() into two stags. In the first
stage, __ceph_flush_snaps() assign snapcaps flush TIDs and add them
to cap flush lists. __ceph_flush_snaps() keeps holding the
i_ceph_lock in this stagge. So inode's auth cap can not change. In
the second stage, __ceph_flush_snaps() send flushsnap cap messages.
i_ceph_lock is unlocked before sending each cap message. If auth cap
changes in the middle, __ceph_flush_snaps() just stops. This is OK
because kick_flushing_inode_caps() will re-send flushsnap cap messages
to inode's new auth MDS.

Signed-off-by: default avatarYan, Zheng <zyan@redhat.com>
parent 7bc00fdd

fs/ceph/caps.c

+102 −83
Original line number Diff line number Diff line
@@ -1247,32 +1247,20 @@ static inline int __send_flush_snap(struct inode *inode, 
 *

 * Called under i_ceph_lock.  Takes s_mutex as needed.

 */

void __ceph_flush_snaps(struct ceph_inode_info *ci,

			struct ceph_mds_session **psession)

static void __ceph_flush_snaps(struct ceph_inode_info *ci,

			       struct ceph_mds_session *session)

		__releases(ci->i_ceph_lock)

		__acquires(ci->i_ceph_lock)

{

	struct inode *inode = &ci->vfs_inode;

	int mds;

	struct ceph_mds_client *mdsc = session->s_mdsc;

	struct ceph_cap_snap *capsnap;

	u32 mseq;

	struct ceph_mds_client *mdsc = ceph_inode_to_client(inode)->mdsc;

	struct ceph_mds_session *session = NULL; /* if session != NULL, we hold

						    session->s_mutex */

	u64 oldest_flush_tid;

	u64 next_follows = 0;  /* keep track of how far we've gotten through the

			     i_cap_snaps list, and skip these entries next time

			     around to avoid an infinite loop */

	u64 oldest_flush_tid = 0;

	u64 first_tid = 1, last_tid = 0;



	if (psession)

		session = *psession;

	dout("__flush_snaps %p session %p\n", inode, session);



	dout("__flush_snaps %p\n", inode);

retry:

	list_for_each_entry(capsnap, &ci->i_cap_snaps, ci_item) {

		/* avoid an infiniute loop after retry */

		if (capsnap->follows < next_follows)

			continue;

		/*

		 * we need to wait for sync writes to complete and for dirty

		 * pages to be written out.
@@ -1283,53 +1271,18 @@ void __ceph_flush_snaps(struct ceph_inode_info *ci, 
		/* should be removed by ceph_try_drop_cap_snap() */

		BUG_ON(!capsnap->need_flush);



		/* pick mds, take s_mutex */

		if (ci->i_auth_cap == NULL) {

			dout("no auth cap (migrating?), doing nothing\n");

			goto out;

		}



		/* only flush each capsnap once */

		if (capsnap->cap_flush.tid > 0) {

			dout(" already flushed %p, skipping\n", capsnap);

			continue;

		}



		mds = ci->i_auth_cap->session->s_mds;

		mseq = ci->i_auth_cap->mseq;



		if (session && session->s_mds != mds) {

			dout("oops, wrong session %p mutex\n", session);



			mutex_unlock(&session->s_mutex);

			ceph_put_mds_session(session);

			session = NULL;

		}

		if (!session) {

			spin_unlock(&ci->i_ceph_lock);

			mutex_lock(&mdsc->mutex);

			session = __ceph_lookup_mds_session(mdsc, mds);

			mutex_unlock(&mdsc->mutex);

			if (session) {

				dout("inverting session/ino locks on %p\n",

				     session);

				mutex_lock(&session->s_mutex);

			}

			/*

			 * if session == NULL, we raced against a cap

			 * deletion or migration.  retry, and we'll

			 * get a better @mds value next time.

			 */

			spin_lock(&ci->i_ceph_lock);

			goto retry;

		}



		spin_lock(&mdsc->cap_dirty_lock);

		capsnap->cap_flush.tid = ++mdsc->last_cap_flush_tid;

		list_add_tail(&capsnap->cap_flush.g_list,

			      &mdsc->cap_flush_list);

		if (oldest_flush_tid == 0)

			oldest_flush_tid = __get_oldest_flush_tid(mdsc);



		if (list_empty(&ci->i_flushing_item)) {

			list_add_tail(&ci->i_flushing_item,

				      &session->s_cap_flushing);
@@ -1339,41 +1292,108 @@ void __ceph_flush_snaps(struct ceph_inode_info *ci, 
		list_add_tail(&capsnap->cap_flush.i_list,

			      &ci->i_cap_flush_list);



		if (first_tid == 1)

			first_tid = capsnap->cap_flush.tid;

		last_tid = capsnap->cap_flush.tid;

	}



	ci->i_ceph_flags &= ~CEPH_I_FLUSH_SNAPS;



	while (first_tid <= last_tid) {

		struct ceph_cap *cap = ci->i_auth_cap;

		struct ceph_cap_flush *cf;

		int ret;



		if (!(cap && cap->session == session)) {

			dout("__flush_snaps %p auth cap %p not mds%d, "

			     "stop\n", inode, cap, session->s_mds);

			break;

		}



		ret = -ENOENT;

		list_for_each_entry(cf, &ci->i_cap_flush_list, i_list) {

			if (cf->tid >= first_tid) {

				ret = 0;

				break;

			}

		}

		if (ret < 0)

			break;



		first_tid = cf->tid + 1;



		capsnap = container_of(cf, struct ceph_cap_snap, cap_flush);

		atomic_inc(&capsnap->nref);

		spin_unlock(&ci->i_ceph_lock);



		dout("flush_snaps %p cap_snap %p follows %lld tid %llu\n",

		     inode, capsnap, capsnap->follows, capsnap->cap_flush.tid);

		__send_flush_snap(inode, session, capsnap, mseq,

		dout("__flush_snaps %p capsnap %p tid %llu %s\n",

		     inode, capsnap, cf->tid, ceph_cap_string(capsnap->dirty));



		ret = __send_flush_snap(inode, session, capsnap, cap->mseq,

					oldest_flush_tid);

		if (ret < 0) {

			pr_err("__flush_snaps: error sending cap flushsnap, "

			       "ino (%llx.%llx) tid %llu follows %llu\n",

				ceph_vinop(inode), cf->tid, capsnap->follows);

		}



		next_follows = capsnap->follows + 1;

		ceph_put_cap_snap(capsnap);



		spin_lock(&ci->i_ceph_lock);

		goto retry;

	}

}



	/* we flushed them all; remove this inode from the queue */

	spin_lock(&mdsc->snap_flush_lock);

	list_del_init(&ci->i_snap_flush_item);

	spin_unlock(&mdsc->snap_flush_lock);

void ceph_flush_snaps(struct ceph_inode_info *ci,

		      struct ceph_mds_session **psession)

{

	struct inode *inode = &ci->vfs_inode;

	struct ceph_mds_client *mdsc = ceph_inode_to_client(inode)->mdsc;

	struct ceph_mds_session *session = *psession;

	int mds;

	dout("ceph_flush_snaps %p\n", inode);

retry:

	spin_lock(&ci->i_ceph_lock);

	if (!(ci->i_ceph_flags & CEPH_I_FLUSH_SNAPS)) {

		dout(" no capsnap needs flush, doing nothing\n");

		goto out;

	}

	if (!ci->i_auth_cap) {

		dout(" no auth cap (migrating?), doing nothing\n");

		goto out;

	}



out:

	if (psession)

		*psession = session;

	else if (session) {

	mds = ci->i_auth_cap->session->s_mds;

	if (session && session->s_mds != mds) {

		dout(" oops, wrong session %p mutex\n", session);

		mutex_unlock(&session->s_mutex);

		ceph_put_mds_session(session);

		session = NULL;

	}

	if (!session) {

		spin_unlock(&ci->i_ceph_lock);

		mutex_lock(&mdsc->mutex);

		session = __ceph_lookup_mds_session(mdsc, mds);

		mutex_unlock(&mdsc->mutex);

		if (session) {

			dout(" inverting session/ino locks on %p\n", session);

			mutex_lock(&session->s_mutex);

		}

		goto retry;

	}



static void ceph_flush_snaps(struct ceph_inode_info *ci)

{

	spin_lock(&ci->i_ceph_lock);

	__ceph_flush_snaps(ci, NULL);

	ci->i_ceph_flags &= ~CEPH_I_FLUSH_SNAPS;

	__ceph_flush_snaps(ci, session);

out:

	spin_unlock(&ci->i_ceph_lock);



	if (psession) {

		*psession = session;

	} else {

		mutex_unlock(&session->s_mutex);

		ceph_put_mds_session(session);

	}

	/* we flushed them all; remove this inode from the queue */

	spin_lock(&mdsc->snap_flush_lock);

	list_del_init(&ci->i_snap_flush_item);

	spin_unlock(&mdsc->snap_flush_lock);

}



/*
@@ -1768,10 +1788,9 @@ void ceph_check_caps(struct ceph_inode_info *ci, int flags, 
						     oldest_flush_tid);

				ci->i_ceph_flags &= ~CEPH_I_KICK_FLUSH;

			}

			if (ci->i_ceph_flags & CEPH_I_FLUSH_SNAPS) {

				__ceph_flush_snaps(ci, &session);

				ci->i_ceph_flags &= ~CEPH_I_FLUSH_SNAPS;

			}

			if (ci->i_ceph_flags & CEPH_I_FLUSH_SNAPS)

				__ceph_flush_snaps(ci, session);



			goto retry_locked;

		}
@@ -2610,7 +2629,7 @@ void ceph_put_cap_refs(struct ceph_inode_info *ci, int had) 
	if (last && !flushsnaps)

		ceph_check_caps(ci, 0, NULL);

	else if (flushsnaps)

		ceph_flush_snaps(ci);

		ceph_flush_snaps(ci, NULL);

	if (wake)

		wake_up_all(&ci->i_cap_wq);

	while (put-- > 0)
@@ -2691,7 +2710,7 @@ void ceph_put_wrbuffer_cap_refs(struct ceph_inode_info *ci, int nr, 
	if (last) {

		ceph_check_caps(ci, CHECK_CAPS_AUTHONLY, NULL);

	} else if (flush_snaps) {

		ceph_flush_snaps(ci);

		ceph_flush_snaps(ci, NULL);

	}

	if (complete_capsnap)

		wake_up_all(&ci->i_cap_wq);

fs/ceph/snap.c

+1 −3
Original line number Diff line number Diff line
@@ -799,9 +799,7 @@ static void flush_snaps(struct ceph_mds_client *mdsc) 
		inode = &ci->vfs_inode;

		ihold(inode);

		spin_unlock(&mdsc->snap_flush_lock);

		spin_lock(&ci->i_ceph_lock);

		__ceph_flush_snaps(ci, &session);

		spin_unlock(&ci->i_ceph_lock);

		ceph_flush_snaps(ci, &session);

		iput(inode);

		spin_lock(&mdsc->snap_flush_lock);

	}

fs/ceph/super.h

+2 −2
Original line number Diff line number Diff line
@@ -890,7 +890,7 @@ extern void ceph_get_cap_refs(struct ceph_inode_info *ci, int caps); 
extern void ceph_put_cap_refs(struct ceph_inode_info *ci, int had);

extern void ceph_put_wrbuffer_cap_refs(struct ceph_inode_info *ci, int nr,

				       struct ceph_snap_context *snapc);

extern void __ceph_flush_snaps(struct ceph_inode_info *ci,

extern void ceph_flush_snaps(struct ceph_inode_info *ci,

			     struct ceph_mds_session **psession);

extern void ceph_check_caps(struct ceph_inode_info *ci, int flags,

			    struct ceph_mds_session *session);